First of all , pls fill " subject " in Your messages .
Regarding the problem you describted : it seems , that you have a lot of
stuff in the vias : residues of unrinsed chemistry , excess of solder mask ,
no-polymerised plugging material .
This problem will hit you regardless of the finishing ( OSP , HASL ,
immersion gold ) .
To my opinion you should check quality of plugged holes .
Regards


At 11:54 21/08/98 -0500, you wrote:
>First of all many thanks for feedback on OSP  and Immersion gold as
>finish -HASL Alternatives.
>
>
>I am looking for info on another problem. The description is as follow:
>
>We are using HASl finish on a board using 15.7 mils and 0603 components.
>(That is why I asked opinion on Finish earlier).
>
>The board is having all the untested vias solder masked  on pads. In
>recent lots from One board vendor, our inspectors have observed black
>residue or coloration on a portion of via . Some of the masked vias are
>having black residue.It appears to be molten mask -turned black from its
>original green color. Some other places, the greenish tinge is reduced
>in intensity and thiose are places where it is affected to lesser
>degree. If we probe or smear gently the blackish portion, the mask comes
>off (peel off) very easily exposing the copper.The material is tacky,
>paste like . Anybody there who can help us what it could be.
>
>The board manufacturer is saying that the residue is non-ionic .
>
>My question is:
>
>- Anybody came across this / similar problem ?Is it common problem with
>masked vias with hole open ?The solder pad is 25 mils and hole is 12
>mils ( 1 mil = one thousandth of an inch).
>
>- the concern for reliability is valid or not --even if the black
>residue --flux or solder mask or any contamination --is passing the
>ionic test.Do you have any suggestions on other tests which we can
>suggest board vendor to carry out ? e.g. SEM ??
>
>Please post your replies on IPC Technet .
>
>thanks
>
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Edward Szpruch
Eltek Ltd - Israel
Tel  972 3 9395050
Fax 972 3 9309581
E-mail :  [log in to unmask]

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